Push-to-talk (PTT) is a two-way communication service that operates like a “walkie talkie.” PTT is half-duplex, meaning communication can only travel in one direction at any given moment. By contrast, a typical cell phone call is full-duplex, meaning both parties can hear each other at the same time. There also exists communication devices that provide both full-duplex and half-duplex capabilities. PTT requires the person speaking to press a button on the communication device while talking and then release it when they are done. The listener then presses a PTT button on their own communication device to respond. Most PTT systems allow group calling, meaning one person can speak to everyone in their assigned or current group at once, just by pressing a PTT key. Some PTT systems use voice-over-IP (VoIP) technology to provide PTT service digitally over digital data networks. Public safety personnel, such as police officers, firefighters and rescue workers to name a few, utilize a variety of different communication devices in the field, including portable handheld radios, cell phones, mobile (vehicular) radios and accessories.
Public safety personnel often desire to listen to multiple PTT groups at one time. Typical solutions managing multiple PTT groups include scanning the groups listed in a scan list by various methods, then playing the audio when traffic is detected. Priorities are usually used in the scan list. Conventional scanning typically involves tuning to different radio frequency (RF) frequencies one by one and staying tuned to a frequency when activity is detected. Trunked scanning typically involves having an infrastructure entity report which groups have activity, with enough information to allow the radio to listen in on desired groups by tuning to a channel. However, both conventional scanning and trunked scanning are prone to missed calls, particularly when there is audio activity on two or more groups.
Accordingly, it would be desirable to improve call management in communication systems that utilize numerous communication devices.
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